Oil burner



A ril 28, 1970 A, HouRwlTg ET AL 3,508,852

OIL BURNER Filed Jan. 2. 1968 FIG. 1

FIG. 3

INVENTOR N A M w w/W H Z n W R U 0 H M A O W V A BOU- FIGA

ATTORNEY United States Patent Office 16 Int. Cl. F23d 11/04 US. Cl.431168 6 Claims ABSTRACT OF THE DISCLOSURE A burner comprising a chamberin which is disposed a rotary cup mounted on a hollow rotating shaftthrough which supply fuel is delivered to the cup and ejected therefromin atomized form, the ejected fuel being vapourized in a first region ofthe chamber and ignited in a second region thereof, a fan for aspiringair to be mixed with the vapourized fuel, a cover spaced above therotary cup, and a fixed body in the form of a conical plate surroundingand spaced outwardly from the rotary cup and cover, the plate beinglocated in the trajectory of the ejected fuel and having air passagesfor the aspired air disposed in the second region of the chamber.

BACKGROUND OF THE INVENTION Field of the invention The present inventionrelates to 'a burner unit of the type in which the fuel is atomized byejection from a rotary cup.

Description of the prior art Burners are known comprising a chamber inwhich is disposed a rotary cup mounted on a hollow rotating shaftthrough which supply fuel is delivered to the cup and ejected therefromin atomized form, the ejected fuel being vapourized in a first region ofthe chamber and ignited in a second region thereof, and a fan foraspiring air to be mixed with the vapourized fuel. See for exampleBritish patent specification 822,288. However the performance of theknown burners is not quite satisfactory in several respects. The blastflame frequently produces soot which is in part deposited in the heatexchanger and flue. Also, a continuous hum is frequently heard duringthe operation of the burner. In addition, startingup the burner may beaccompanied by a loud noise together with an ejection of smoke caused bythe explosion and incomplete combustion of residue fuel already in theburner.

Objects of the present invention are to provide improvements in one ormore of the above respects in a burner unit of the rotary cup type.

SUMMARY OF THE PRESENT INVENTION According to the invention, the burnerof the foregoing type includes a cover spaced above the rotary cup, anda body surrounding and spaced outwardly from the rotary cup and thecover. This body is located in the trajectory of the ejected fuel andhas air openings in the path of the aspired air. The body is spaced atsuch distance from the rotary cup that the air openings are located inthe second region (i.e. where the fuel is ignited) of the chamber andalso in the trajectory of the ejected fuel, whereby freshly arrivedvapourized fuel is ignited immediately upon meeting the air in thevicinity of said air openings.

It has been found that with this arrangement the resulting flame iscompletely blue and virtually no soot is produced, and further that thefuel burns without humming.

Patented Apr. 28, 1970 According to another feature, the burner mayinclude a conduit for introducing start-up fuel to the ignition devicebefore the supply fuel arrives at the rotating cup, the flow of thestart-up fuel being discontinued after the supply fuel is ignited. Thisfeature has been found to solve the problem of the loud noise and theejection of smoke usually occurring upon starting-up the known burners.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated, by wayof example only, in the accompanying drawings in which FIGS. 1 and 2show in elevational section two forms of a burner unit according to theinvention; FIG 3 schematically shows the circuit that may be used forthe unit of FIG. 2; and FIG. 4 shows a modification of the burner unit.

DESCRIPTION OF THE PREFERRED EMBODIMENT The burner unit illustrated inFIG. 1 comprises a supporting casing 1 merging into a superposed sleevepart 2. Casing 1 comprises a core 3 supporting an electric resistor 4coiled on a refractory support and serving as the ignitor. A hollowshaft 7 whose lower portion is connected to an electric driving motor(not shown) passes through bores 5 and 6 in the bottom of the casing andthe core, respectively. The lower end of shaft 7 is connected to a fuelsupply. Keyed on shaft 7 is a fan 8 rotatable within a hollow space 9 ofeasing 1 and serving for the aspiration of air through a plurality ofbores 10 provided in the bottom of casing 1, the aspired air beingdelivered through ducts 12 for admixture with the fuel.

Mounted on the upper, delivery end of shaft 7 and in chamber 13 of theburner is a rotary cup 14 which is covered from above by means of atray-shaped cover 15 supported by a ring 16 resting on stays 17. Theaggregate 15, 16, 17 is surrounded by a fixed annular or conical plateor bowl 18. The wall of bowl 18 is inclined so as to be in thetrajectory of the fuel ejected from cup 14 and is formed with aplurality of openings or vents 19 arranged in a circular array aroundcup 14 and cover 15 and also in the trajectory of the ejected fuel. Eachvent 19 is surrounded by a rim 20. Bowl 18 rests on a sleeve 21, therebeing an annular free space 22 between sleeve 21 and heater 4 mergingbelow into a space 23 of increased diameter. A duct 24 from space 23 isconnected to a tube 25 and serves as a return to the fuel supply of anynon-burnt fuel. On the flame producing side of bowl 18 is mounted adeflector 26 for the concentration and direction of the blast flame.

The operation of the burner unit is as follows: When shaft 7, fan 8, androtary cup 14 rotate, fuel is delivered from the fuel tank through theshaft to the rotary cup 14 and is ejected into chamber 13 in atomizedform. At the same time the rotation of fan 8 causes air to flow throughducts 10, ducts 12 and openings 19.

At the beginning of the operation the fuel is ignited by resistor coil 4and thereafter the flame maintains itself by the continuous supply offuel and air. The flame surrounds cover 15 which is therefore in a hotstate throughout the operation of the burner. In consequence, chamberregion 13' is heated and the atomized fuel ejected from the rotary cup14 is vapourized therein. The temperature of chamber region 13" in whichcombustion takes place is higher, suflicient to sustain combustion offreshly arriving vapourized fuel. Any non-vapourized fuel impinging onbowl 18 drips down through spaces 22 and 23, and is returned throughduct 24 to the fuel tank. The returning liquid fuel is prevented fromdripping through vents 19 by rims 20.

The vapourized fuel delivered from region 13 impinges on the surface ofbowl 18 in the vicinity of openings 19. The location of bowl 18 is suchthat openings 19 are located in chamber region 13 where the temperatureis sufiiciently high to sustain combustion of the freshly arrivingvapourized fuel. The latter is therefore ignited as soon as it meets theair passing through the openings. Because this ignition occurssimultaneously with the meeting of the vapourized fuel and air, asoot-free silent blue flame is produced. Moreover, since anynon-vapourized fuel that there may be is returned to the tank and doesnot participate in the combustion, this also contributes to thesoot-free, blue character of the flame.

In starting-up, the current to the ignitor resistance is switched on ashort time before the fuel arrives at the cup. Thus when fuel startsdripping from the cup the resistor is already hot and glowing. It wasfound that the fuel which remained in the vicinity of the cup on themetal parts of the burner at the time the resistor coil was ignitedsometimes caused a small explosion, or a smouldering of the fuel, whichgave rise to an especially loud noise, and/or an ejection of smoke fromthe burner.

These undesirable effects are avoided by the modification illustrated inFIG. 2. Here an oil conduit 30 is provided, terminating in a spout 31overlying the ignitor resistor 32, which in this case is positionedeccentrically in relation to the rotating shaft 7 of the burner. Aconcentric resistor, such as resistor 4 in FIG. 1, could of course alsobe used. In FIG. 2, the deflector 26 is omitted, but the remaining partsare the same as in FIG. 1 and therefore have been referred to by thesame reference numerals.

The electrical wiring for operating the burner of FIG. 2 isschematically illustrated in FIG. 3. It includes a switch 35 whichpermits the flow of current to the ignitor resistance (4 or 32). Themotor M for driving shaft 7 and the pump P for supplying the startingfuel through conduit 30 are controlled through a time-delay device TD(eg a slow-acting relay) such that: the ignitor resistor is firstheated; a short time thereafter the starting fuel is pumped throughconduit 30 so as to drip onto the glowing heater and to ignite; and thena short time thereafter the supply fuel arrives at the rotating cup 14and is vapourized and ignited in the manner described earlier. Once thesupply fuel is ignited, the electric current to the ignitor and also tothe pump for the starting fuel are both switched olf by a control switch36. The latter may be operated in a known manner, e.g. after apredetermined time delay, or in response to the air pressure created bythe fan or the burner. Instead of pumping the starting fuel by a pump,it may be gravity-fed and controlled by a valve.

While the cover 15 in FIGS. 1 and 21s shown as being fixed to body 18,it could also be fixed (by stays equivalent to 17) to cup 14 so as torotate therewith, whereupon the cover is preferably dished outwardly,instead of inwardly as shown in FIGS. 1 and 2, and may be ofapproximately the same diameter as the cup. This is illustrated in FIG.4, wherein it is seen that the cover 15 is of outstay 17' so thatit"rotates with the cup.

Further variations and embodiments of the invention will be apparent.

What is claimed is:

1. A burner comprising a chamber in which is disposed a rotary cupmounted on a hollow rotating shaft through which supply fuel isdelivered to the cup and ejected therefrom in atomized form, the ejectedfuel being vaporized in a first region of the chamber and ignited inasecond region thereof, and a fan for aspiring air to be mixed with thevaporized fuel, characterized in that said burner includes a coverspaced above the rotary cup, and a fixed annular body surrounding andspaced outwardly from the rotary cup, said fixed annular body having awall inclined with respect to the rotary cup and being formed with acircular array of openings for the aspired air surrounding said cup andcover, the said annular body and the circular array of air openingstherein being located in the trajectory of the ejected fuel and in saidsecond region of the chamber whereby freshly arriving vaporized fuel isignited immediately upon meeting the air passing through said airopenings.

2. A burner as defined in claim 1, wherein said fixed annular body is inthe form of a conical plate surrounding the rotary cup and cover.

3. A burner as defined in claim 1, wherein each air opening issurrounded on the flame producing side of said body with a rim adaptedto prevent the dripping of any non-vaporized fuel through the opening.

4. A burner as defined in claim 1, wherein said cover is fixed to saidbody.

5. A burner as defined in claim I, wherein said cover is fixed to saidrotary cup so as to rotate therewith.

6. A burner as defined in claim 1, further including a start-up ignitiondevice, a conduit for introducing startup fuel to said ignition devicebefore the supply fuel arrives at the rotating cup, and means fordiscontinuing the flow of the start-up fuel after the supply fuel isignited.

References Cited UNITED STATES PATENTS 396,525 1/1889 Bains 431 210855,688 6/1907 Blubaugh 431-285 1,497,829 6/1924 Allen et a1 431-168 X1,544,208 6/1925 Bennett 239 214.13 1,695,030 12/1922; Scheminger 4311682,374,290 4/1945 Johansson 431 117 x 2,507,006 5/1950 Hammellet al. 239214.17

FOREIGN PATENTS 644,522 7/1962 Canada.

EDWARD G. FAVORS, Primary Examiner US. Cl. X.R.

